HVAC - complemplating a split ductless

I have two AC zones in my house one for the west wing and one for the east
wing. The west wing is a 4 ton cooling the living room, dinning room,
kitchen, laundry room, utility room, pantry, one bath and a hallway. The
east side is a 3.5 ton cooling 4 bedrooms, 3 baths and a long hallway. In
the middle connecting the east and west wing is a family room which is about
32'x16' with the ceiling varying from 9' to 16' tall. This room has a
fireplace and lots of glass doors and windows that leads to the pool and
it's never cool enough and it's at the end of the AC supply for the east
wing.
So I am thinking of capping off the supply for the family room and let the
other rooms get cooler and install a split ductless unit (like a Mitsubishi
Mr. Slim Series MXZ-2A20NA for example). I have calculated I need 20,000
BTU. I don't think I will need a heat pump since I am in Miami and I do
have a fireplace in that room if I ever need it.
Questions are:
(1) What are other brands I should consider?
(2) These unit needs an outside condenser too do they need to be floor
mounted on a concrete pad or they need to be wall mounted?
(3) Where should I place this unit on the inside? I assume it has to be
placed in the middle and as high as possible) but I have a tied beam and a
row of windows and glass door and the only spot is the corner, but I am
concerned putting it in the corner will cause uneven distribution of the
cooling, the AC guy who quoted me says it does not matter air will flow
evenly...really? Seems illogical to me if the room is 32' long it will not
cool evenly if it's mounted on one side right?
Thanks,
MC

Hi MC,
(1) I'd add Fujitsu and Friedrich to the list as well. Fujitsu's
inverter models have SEER ratings in the low 20's.
(2) The outdoor compressor can be installed either at grade level or
wall mounted. Bear in mind that wall installations can potentially
result in noise transmission through the building structure and that
at grade level you can use landscaping and other architectural
elements to visually hide the hardware and help dampen any operating
noise.
(3) Ideally, the indoor air handler should be placed where it would
have the greatest projection/throw. Nonetheless, they're equipped
with air vanes that can be easily adjusted via the remote control to
shift the direction of the conditioned to one side or the other as
required.
Cheers,
Paul

Something to keep in mind. I have a 25yrs in the business HVAC company
owner do work on any of these HUD wrecks I rebuild. In this particular
place now, a totally new system was installed. Told him I'd be shutting
vents in unused areas. Right away he said to be careful because the coil
is designed to have x number of cubic of air passing over it in a given
time, Anything less is not good. I failed to ask him if it was bad for
the unit and/or if it was an efficiency unit. My GUESS is both.
This particular 2-1/2t gas pack has 12 floor/low wall ducts. Ten are 6"
and two are 8" The two 8" plus a 6" were put in the room with a vaulted
15' ceiling. I believe he said I could close three 6" ducts but it may
have been only two. Anyway, I have two closed in one room I only use for
storage right now.

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